Refrigeration system and method employing an air-suspended compressor

Abstract

The application belongs to the technical field of compressor and refrigeration, and particularly relates to a refrigeration system and method using a gas suspension compressor. The refrigeration system comprises: a primary compressor connected with an evaporator; a secondary compressor connected with the primary compressor through an inter-stage pipeline; an outlet of the secondary compressor is divided into two paths, one path is connected with a gas suspension bearing through a second regulating valve and a bearing gas supply port, and the other path is connected with a flash tank through a condenser and an ejector; and the flash tank is divided into three paths, one path is directly connected with the inter-stage pipeline, one path is connected with a motor shell through a first regulating valve, and one path is connected with the primary compressor through an expansion valve and the evaporator. The refrigeration system can reduce power consumption in the bearing gas supply process, ensure the superheat degree of the bearing gas supply, reduce the refrigerant flow in the motor cooling process, reduce the power consumption in the compression process of the mixed gas in the motor cavity, and further improve the system performance.

Description

Technical Field

[0001] This invention belongs to the field of compressor and refrigeration technology, specifically relating to a refrigeration system and refrigeration method using an air suspension compressor. Background Technology

[0002] Centrifugal refrigeration compressors employing air-bearing systems offer advantages such as high speed, low power consumption, and simple structure, significantly improving refrigeration system efficiency and representing an important development direction for refrigeration systems. Among these, static pressure air-bearing systems, with their high load-bearing capacity and stable reliability, show promising application prospects in refrigeration systems. When using compressors with static pressure air-bearing systems, separate bearing air supply systems and motor cooling systems are required.

[0003] The existing bearing gas supply solution involves adding a receiver tank with a heater after the condenser. A refrigerant branch is added at the condenser outlet, pumping a portion of the refrigerant to the receiver tank, where electric heating generates high-pressure gas for bearing gas supply. The technical drawback of this solution is that heating the liquid into gas consumes heat, and the resulting saturated vapor may expand and condense into liquid as it flows through pipes, valves, and inside the bearing. This poses a risk of liquid droplets within the bearing clearance, potentially causing bearing instability or damage.

[0004] The existing cooling solution for high-speed motors involves directly introducing liquid refrigerant from the condenser into the motor housing to cool the stator, and then into the motor cavity to cool the rotor. The drawbacks of this solution are: the high pressure and temperature of the refrigerant in the condenser result in a small temperature difference during the cooling process, affecting the cooling effect. Furthermore, the higher pressure of the liquid refrigerant leads to a larger enthalpy and lower latent heat, resulting in a larger refrigerant flow rate for cooling the motor and a reduced system cooling capacity.

[0005] In existing motor cavity return gas schemes, the exhaust gas from the bearings and the gas cooled by the motor are mixed in the motor cavity and then returned to the evaporator to complete the gas supply and cooling cycle. The drawback of this scheme is that after the gas in the motor cavity enters the evaporator, it needs to undergo a two-stage compression process before entering the condenser and further completing the bearing gas supply and motor cooling cycle. This process consumes a significant amount of compressor power. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems existing in the prior art, and to propose a refrigeration system and refrigeration method using an air suspension compressor. This refrigeration system can reduce the power consumption of the bearing air supply process, ensure the superheat of the bearing air supply, reduce the refrigerant flow rate of the motor cooling process, reduce the power consumption of the mixed gas compression process in the motor cavity, and thus improve the system performance.

[0007] The technical solution of this invention is:

[0008] This invention protects a refrigeration system employing an air-suspension compressor, comprising:

[0009] A primary compressor, which is connected to an evaporator;

[0010] The secondary compressor is connected to the primary compressor via an interstage pipeline; the outlet of the secondary compressor is divided into two paths, one of which is connected to the air suspension bearing after passing through the second regulating valve and the bearing air supply port; the other path is connected to the flash tank after passing through the condenser and the ejector.

[0011] The flash tank has three outlets: one directly connects to the interstage pipeline, one connects to the motor housing through the first regulating valve, and the other connects to the first-stage compressor through the expansion valve and the evaporator.

[0012] Furthermore, an ejector is provided at the outlet of the condenser, and a flash tank is provided at the outlet of the ejector; that is, the outlet of the condenser is connected to the inlet of the ejector, and the outlet of the ejector is connected to the inlet of the flash tank.

[0013] Furthermore, a return air port is provided on the motor housing, and the return air port is connected to the injector.

[0014] This invention also protects a refrigeration method using the refrigeration system, wherein the liquid in the flash tank is used for motor cooling, and part of the gas discharged from the secondary compressor passes through the second regulating valve and enters the working gap of the air suspension bearing through the bearing gas supply port to support the high-speed operation of the rotor; the remaining gas discharged from the secondary compressor is condensed by the condenser and enters the ejector, which then ejects low-pressure gas from the return gas port into the flash tank.

[0015] Furthermore, the flash steam from the flash tank enters the interstage pipeline for interstage gas replenishment.

[0016] Furthermore, the liquid in the flash tank is divided into two parts. One part of the liquid enters the motor housing through the first regulating valve to cool the motor stator, and then enters the motor interior to cool the motor rotor. The gas after heat exchange is mixed with the exhaust gas from the air suspension bearing in the motor cavity and enters the ejector through the return gas port. The other part of the liquid enters the evaporator through the expansion valve, and after heat exchange and evaporation, it enters the first-stage compressor.

[0017] The beneficial effects of this invention are:

[0018] The refrigeration system using an air-suspension compressor provided by this invention has an ejector at the condenser outlet and a flash tank at the ejector outlet. The liquid refrigerant inside the flash tank is used for motor cooling, while part of the high-pressure gas from the outlet of the secondary compressor is used for bearing gas supply. The low-pressure exhaust of the two is mixed inside the motor cavity and then enters the ejector. After being ejected by the high-pressure refrigerant at the condenser outlet, it enters the flash tank. The gas in the flash tank enters the interstage pipe of the two-stage compressor, while the liquid is partly used for motor cooling and partly enters the evaporator for refrigeration.

[0019] This refrigeration method reduces the electric heating power required for bearing gas supply. Furthermore, the mixed gas inside the motor cavity is ejected into the interstage of the two-stage compressor, completing the cycle only through the compression process of the high-pressure stage compressor, thus reducing power consumption during compression. The liquid temperature inside the flash tank is lower than that inside the condenser, increasing the heat exchange temperature difference during motor cooling. Because the pressure inside the flash tank is lower, the enthalpy of the liquid inside is smaller, and the latent heat of vaporization is greater, the refrigerant flow rate used for motor cooling can be reduced, increasing the system's cooling capacity. Attached Figure Description

[0020] Figure 1 A schematic diagram of a refrigeration system using an air-suspension compressor provided by the present invention;

[0021] In the above diagrams, 1. Condenser; 2. Ejector; 3. Flash tank; 4. Expansion valve; 5. Evaporator; 6. First regulating valve; 7. Interstage piping; 8. Return port; 9. Air suspension bearing; 10. Second stage compressor; 11. Bearing air supply port; 12. First stage compressor; 13. Motor housing; 14. Second regulating valve. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To further understand the present invention, it will be further described in conjunction with the accompanying drawings and embodiments.

[0024] Example 1

[0025] like Figure 1 As shown, this embodiment provides a refrigeration system using an air-suspension compressor. The refrigeration system includes a condenser 1, an ejector 2, a flash tank 3, an expansion valve 4, an evaporator 5, and a first-stage compressor 12 connected in sequence. The first-stage compressor 12 and the second-stage compressor 10 are connected by an interstage pipe 7.

[0026] An ejector 2 is installed at the outlet of condenser 1, meaning the outlet of condenser 1 is connected to the inlet of ejector 2. The high-pressure liquid inside condenser 1 is used to eject the low-pressure gas from the motor cavity. A flash tank 3 is installed at the outlet of ejector 2, meaning the outlet of ejector 2 is connected to the inlet of flash tank 3. One gas outlet of flash tank 3 is directly connected to the interstage pipe 7 between the two-stage compressor. The vapor flashed inside flash tank 3 enters the interstage pipe 7 for interstage makeup gas.

[0027] The other two paths of the flash tank 3 are liquid passages. One path is connected to the motor housing 13 through the first regulating valve 6, and the other path is connected to the first-stage compressor 12 through the expansion valve 4 and the evaporator 5.

[0028] The outlet of the secondary compressor 10 is divided into two paths. One path connects to the second regulating valve 14 and the bearing gas supply port 11 in sequence, and then connects to the air suspension bearing 9. The other path passes through the condenser 1 and the ejector 2 and then connects to the flash tank 3. The gas suspension bearing is located inside the motor cavity. A spiral cooling channel is provided inside the motor housing 13. A return gas port 8 is provided on the motor housing 13, and the return gas port 8 is connected to the ejector 2.

[0029] Example 2

[0030] This embodiment provides a refrigeration method using this refrigeration system, specifically:

[0031] After the system is running stably, part of the high-pressure gas from the secondary compressor 10 passes through the second regulating valve 14 and enters the working gap of the air suspension bearing 9 through the bearing supply port 11 to support the high-speed operation of the rotor; the remaining high-pressure gas discharged from the secondary compressor 10 is condensed by the condenser 1 and enters the ejector 2, which then ejects the low-pressure gas from the return gas port 8 into the flash tank 3.

[0032] The flash steam in flash tank 3 enters the interstage pipe 7 between the primary compressor 12 and the secondary compressor 10 for interstage replenishment. The liquid in the tank is divided into two parts. One part of the liquid enters the spiral cooling channel inside the motor housing 13 through the first regulating valve 6 to cool the motor stator, and then enters the motor interior to cool the motor rotor. The gas after completing the heat exchange process mixes with the exhaust gas from the air suspension bearing 9 in the motor cavity, and then enters the ejector 2 through the return port 8. The other part of the liquid in flash tank 3 enters the evaporator 5 through the expansion valve 4, and after heat exchange and evaporation, enters the primary compressor 12 to complete the system cycle.

[0033] In this refrigeration method, the liquid in the flash tank 3 is used for motor cooling, while the high-pressure gas from the outlet of the secondary compressor 10 is used for bearing gas supply. The low-pressure exhaust gases from both mix inside the motor cavity and then enter the ejector 2. After being ejected by the high-pressure refrigerant from the outlet of the condenser 1, they enter the flash tank 3. This method reduces the electric heating power required for bearing gas supply, and the mixed gas inside the motor cavity, after being ejected, enters the interstage pipe 7 between the primary compressor 12 and the secondary compressor 10, completing the cycle only through the compression process of the high-pressure compressor, thus reducing the compressor's power consumption.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, alterations, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A refrigeration system employing an air-suspension compressor, characterized in that, It includes a condenser, ejector, flash tank, expansion valve, evaporator, and first-stage compressor connected in sequence. The first-stage compressor and the second-stage compressor are connected by interstage piping. An ejector is installed at the outlet of the condenser, that is, the outlet of the condenser is connected to the inlet of the ejector, and the high-pressure liquid in the condenser is used to eject the low-pressure gas in the motor cavity; a flash tank is installed at the outlet of the ejector, that is, the outlet of the ejector is connected to the inlet of the flash tank (3), and one gas outlet of the flash tank is directly connected to the interstage pipeline between the two-stage compressors. The steam flashed in the flash tank enters the interstage pipeline for interstage gas replenishment. The other two paths of the flash tank are liquid passages. One path is connected to the motor housing through the first regulating valve, and the other path is connected to the first-stage compressor through the expansion valve and the evaporator. The outlet of the secondary compressor is divided into two paths. One path is connected to the second regulating valve and the bearing gas supply port in sequence, and then to the air suspension bearing. The other path is connected to the flash tank after passing through the condenser and the ejector. The gas suspension bearing is located inside the motor cavity. A spiral cooling channel is provided inside the motor housing. A return gas port is provided on the motor housing and is connected to the ejector.

2. The refrigeration method of the refrigeration system according to claim 1, characterized in that, The liquid in the flash tank is used for motor cooling. Part of the gas discharged from the secondary compressor passes through the second regulating valve and enters the working gap of the air suspension bearing through the bearing supply port to support the high-speed operation of the rotor. The remaining gas discharged from the secondary compressor is condensed by the condenser and enters the ejector, which then ejects the low-pressure gas from the return port into the flash tank.

3. The refrigeration method of the refrigeration system according to claim 1, characterized in that, The flash steam from the flash tank enters the interstage pipeline for interstage replenishment.

4. The refrigeration method of the refrigeration system according to claim 1, characterized in that, The liquid in the flash tank is divided into two parts. One part of the liquid enters the motor housing through the first regulating valve to cool the motor stator, and then enters the motor interior to cool the motor rotor. The gas after heat exchange is mixed with the exhaust gas from the air suspension bearing in the motor cavity and enters the ejector through the return gas port. The other part of the liquid enters the evaporator through the expansion valve, and after heat exchange and evaporation, it enters the first-stage compressor.

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